Researches On Commutation Correction Technology For High-speed Permanent Magnetic Brushless DC Motor

Recently,high-speed permanent magnet brushless dc motor(BLDCM)is characterized by simple control,low cost,high efficiency,small size,and high power density,which develops rapidly.However,the commutation error is one of the main factors that degrades the performances of high-speed permanent magnet BLDCM,limiting the development of BLDCM in some applications where need higher speed,higher accuracy and higher stability of the motor.Thus,researches on commutation correction technology for high-speed permanent magnet BLDCM are very important.First,this paper presents the principle of commutation of BLDCM and analyzes the main types of commutation errors with their mathematical modes.Then,it unifies different types of commutation errors by pointing out that they are reflected as the phase difference between the back electromotive force(back-EMF)and the phase current,and the phase difference is the internal power factor angle.Then,this paper proposes a commutation correction strategy based on the phase-looped of the internal power factor angle.This strategy obtains the internal power factor angle indirectly by observing the phase difference between the rotor flux and the phase current integral.Then the internal power factor angle is used as the control and feedback signal to establish a phase-locked loop(PLL)with the use of PI regulator.This strategy can compensate for the commutation errors caused by various factors uniformly with simple control.Next,this paper proposes a self-optimization commutation correction strategy based on tracking the minimum phase current.By presenting that the phase current is continuous derivable and has a minimum only when the commutation error is fully compensated as the commutation error changes,the self-optimization algorithm for the commutation compensation angle is established,that is to take the phase current as the feedback signal to automatically optimize the commutation compensation angle.This strategy can compensate for the commutation errors caused by various factors as well,and needs to detect the motor phase current only,and is independent from the motor parameters.Finally,simulation models of the two commutation correction strategies proposed in this paper are built through MATLAB/Simulink,and TMS320F28335 is used to establish the experimental platform for the two strategies.The simulation and experimental results prove the feasibility and effectiveness of the two strategies respectively.